Fluid actuated tool



Dec. 3, 1957 w. A. GERRANS FLUID ACTUATED Toor.

2 Sheets-Sheet 1 Filed July 5. 1955 iff/14,144]

Il l' ATTORNEYS Dec. 3, 1957 W. A. GERRANSA FLUID ACTUATED TOOL 2Sheets-Sheet 2 Filed July 5. 1955 ATTORNEYS Unite States Patent2,814,872 FLUID ACTUATED TOOL William A. Gerrans, Colusa, Calif.Application July 5, 1955, Serial No. 520,057 2 Claims. (Cl. 30-228) Thisinvention relates to manually manipulated tools and more particularly toa fluid actuated tool which is adapted for heavy duty work. Although theinvention will be described as embodied in a pair of pruning shears, itwill be understood that the novel features of construction and method ofoperation lend themselves to use in other devices.

Heretofore various attempts have been made to evolve power drivenpruning shears and like tools, but thus far few practical structureshave been achieved. In some devices there has been an attempt to employcompressed air for actuating the tool, but the resulting structure hasusually been slow in operation and capable of only light duty. The fewattempts to employ a liquid such as oil, as opposed to air and otheruids, have not been successful mainly because the resulting structureshave been too cumbersome for manual manipulation, or if made withinreasonable size limits, have not provided sucient power for heavy dutywork.

It should be noted that a device which purports to lend itself to usewith any fluid, including oil, must not be provided with an exhaustpo-rt. Thus, when oil is employed as the uid medium, it is necessarythat the exhaust oil be returned to the power means although if air isused it may be discharged into the atmosphere.

Another shortcoming of prior art devices is that, in general, they arenot readily manipulated manually. In the case of pruning shears forexample, it is desirable that the cutting blades be arranged to turnrelative to the power cylinder, so that the operator can, with one hand,direct the cutting blade at any desired angle While maintaining a iirmhold on the power cylinder with the other hand.

The main object of the present invention is therefore to overcome thedisadvantages of prior art devices of like nature.

Another object of the invention is the provision of a uid actuated toollending itself to use with any uid including oil and other liquids andwhich does not discharge the operating fluid out of the mechanism.

Still another object of the invention is the provision of a fluidactuated tool such as pruning shears which is constructed so that theworking head is swivelly mounted to facilitate manual handling of thetool in various positions.

Other objects and advantages will be seen in the following specicationand in the drawings.

Fig. l is a part sectional part elevational view of the hydrauliccylinder end of a pair of iluid actuated pruning shears showing oneembodiment of the invention.'

Fig. 2 is a continuation of the pruning shears of Fig. 1 showing theworking end of the same. Figs. 1 and 2 are considered as one view andare separated so as to accommodate the view to the sheet.

Fig. 3 is a schematic piping and wiring diagram of the invention.

Figs. 4 and 5 are similar to Figs. 1 and 2, but show a modified form ofthe invention.

In detail, and referring to Figs. l and 2, the invention comprises ahydraulic cylinder generally designated 1. The rear end of cylinder 1,that is, the end remote from the working head of the tool, is providedwith the removable plug 2 to which is secured a handle 3 by which thedevice may be grasped in one hand of the operator.

' Mounted on handle 3 is a switch 4 and a switch arm ice 5 which may beconveniently actuated by the operator. The function of switch 4 will besubsequently described in connection with the piping and wiring diagram.

At the forward end of cylinder 1 is a closure plug 6 which may bescrewthreadedly secured to the cylinder (Fig. l). If desired, a packingelement 7 may be interposed between cylinder 1 and plug 6 to preventleakage out of said cylinder.

Plug 6 is provided with a threaded opening for receiving therein thethreaded fitting 8 of a supply conduit 9 through which iuid, such asoil, is conducted to the forward end of cylinder 1.

Reciprocable within cylinder 1 is a piston 10 to which is secured apiston rod 11 extending through a bore 12 in plug 6. A packing element,such as an O-ring 13 may be provided to prevent leakage of oil throughbore 12 and past piston rod 11.

The plug 6 is centrally recessed as at 14, to permit oil under pressurefrom conduit 9 to be impressed on the forward, or piston rod side ofpiston 10. Piston 10 may be provided with any suitable packing means,such as O-ring 15, to prevent leakage therepast. In order to vent therear end of cylinder 1, one or more holes 16 may be provided in thesidewall of said cylinder adjacent rear end plug 2.

Swivelly secured to plug 6 of cylinder 1 is a tubular extension membergenerally designated 19 which is preferably made in two sections 20, 21.Section 20 is preferably provided at its forward end with a bearingblock 22 (Fig. 2) which may be rigidly secured to section 20 by weldingor brazing as indicated at 23. The forward section 21 of the extensionmember 19 is provided at its rear end with a nut 24 integrally securedto said section 21 by welding or brazing. Nut 24 and bearing block 22are complementarily threaded to permit the sections to be releasably,but securely attached together (Fig. 2). To further facilitate assemblyand disassembly of the device, section 21 may be made in two partsconnected by a coupling 25.

Fixedly secured to the forward end of section 21 of the extension is afixed work element such as a pruning blade 26.

Referring again to Fig. 1, the piston rod 11 is provided at its outer orforward end with a plug 30 which may be screwthreadedly secured to thepiston rod 11. In alignment with piston rod 11 is a linkage rod 31providedwith a swivel collar 32 rigidly secured thereto as by soldering.The collar 32 is received within a swivel cap 33 which in turn isscrewthreadedly secured to the plug 30. By this structure it will beseen that the linkage rod 31 may rotate freely within cap 33. To insureagainst loosening of the above described elements a pin 34 may be pressfitted into a through bore extending transversely of the plug 30 and cap33.

lnterposed between plug 30 on connecting rod 11 and the end plug 6 oncylinder 1 is a helical compression spring 35 which urges the piston 10in a forward direction at all times.

Linkage rod 31 passes through a bore 37 in the bearing block and isreciprocable therein. Thus, said linkage rod is slidably supported atboth of its ends to facilitate reciprocation within the extension member19. A second linkage rod 38 may be connected end to end with rod 31(Fig. 2), but rods 31 and 38 act as if they were one rod.

The forward end of rod 38 is connected by a pin 39 to one end of anactuating arm 40 which in turn is pivotally secured by bolt 41 to oneend of a movable blade 42 Movable blade 42 is swingably secured to fixedblade 26 by a bolt 43. Slot 44 is provided in extension section 21 forpassing arm 40.

By the above described structure it will be apparent upon theintroduction of fluid into cylinder 1 through conduit 9 the piston 10will be forced rearwardly (to the left, Fig. 1) causing blade 42 toswing into cutting engagement with blade 26. At the same time spring 35is compressed so that upon release of pressure of the uid in conduit- 9,blade 42 will return to its normal inoperative position of Fig. 1.

Referring now to Fig. 3, conduit 9 is connected to a three way valve 48of the solenoid actuated type. The solenoid of valve 48 is in a circuit49 which includes `a source of electrical power 50 and switch 4hereinbefore referred to (Fig. 1).

Oil is received in a reservoir 51 which may conveniently be placed on atractor (not shown) together with the other apparatus to be described.Oil is pumped from reservoir 51 through pipe 57 and through a suitablerelief valve 52 by pump 53 to an accumulator 54. Accumulator 54 may beset for the proper working pressure of the shears (up to about 1000 p.s. i.) and is connected with the Pressure side of the three way valve48.

A suitable overload valve 55 and check valve 56 may be provided as shownin Fig. 3. The return from the valve 48y is through conduit 58 toreservoir 51 and the return from valve 55 is through conduit 59.

The provision of the three way solenoid actuated valve 48 permits fastaction of the shears. When the operator desires to cut a branch, hemerely positions the blades 26, 42 in proper position and squeezes onswitch arm 5 to close switch 4. Upon release of said switch 4 valve 4Sdisconnects conduit 9 from pressure conduit 57 and connects it withreturn conduit 58 thereby permitting spring 35 to return the blades 26,42 to open position and move piston forwardly. The spring 35 must ofcourse be relatively strong to exhaust cylinder 1 of oil and return theshears to the normal inoperative position.

The action of the blades is much faster when oil is employed than whencompressible air is used. However, it will be apparent that the devicemay be operated with air as well as with liquids.

An extremely important feature of the invention resides in the fact thatthe extension 20, 21 may swivel relative to the cylinder 1. For thispurpose the rear end of extension section is provided with an integralcollar 62 similar to collar 32 on rod 31 and a plug 63 is threadedlysecured in the forward end of plug 6 on cylinder 1. Plug 63 is bored toreceive section 20 therethrough and collar 62 is. permitted to rotatewithin the space between plugs 6 and 63. Axial thrust on section 20 isof course taken bythe rear end of plug 63 and the forward end of plug 6just as axial thrust is taken by cap 33 and plug 30 from collar 32.

By the above described structure it will be apparent that the operatormay maintain the same grip on the handle 3 with one hand and turn theextension 19 as desired with the other hand to suit the position of thebranches to be cut. It should also be noted that relatively littleresistance to turning extension 19 will be experienced because of theexistence of the two swivels 32 and 62. The pressure of the fluid andthe force of the spring are not transferred to the` swivelling parts andthis is very important because of the very high loads that may beinvolved.

A modied form of the invention is shown in Figs. 4, 5 which is adaptedfor somewhat lighter duty than the structure of Figs. 1, 2. In this casethe blade positions are changed so that the iixed blade 70 is secured tobutt alongside extension 71.. Movable blade 72 is connected by means ofa linkage generally designated 73 with the forward end of the piston rod74 of piston 75. In this case, forward movement of the piston (towardthe working head) is required to cause the working stroke.

The rear section 76 of extension 71 may be bored out to provide acylinder in which piston 75 is reciprocable. The handle 77 of this formof the invention may be formed with an enlargement 78 extendingcoaxially toward piston 75, from handle 77.

Threadedly secured to the rear end of section 76 is a swivel nut 8i)which is formed with an annular shoulder 8l abutting the enlargement 78of handle 77 The spring 79 acts between the bearing block 82 ofextension 71 and piston 75 -to urge the latter into engagement with ashoulder 83 formed in swivel nut 80. By this structure the force of thespring 79 is not brought to bear through the shoulder 81 against theenlargement 78 of handle 77. In other words, there is no resistance toswivelling the extension relative to the handle except the resistancecreated by the O-ring or other sealing element 84. Of course when theoil pressure is brought to bear on piston 75 the force of frictionresisting swivelling is enlarged, but it is never desired to swivel theextension when the pressure is on. It should be noted in this connectionhowever, that in the heavy duty form of Figs. 1, 2 the sealing meansdoes not resist swivelling of the extension relative to the cylindermember. ln other respects the pruning shears of Figs. 4, 5 is similar tothat of Figs. 1, 2 and the piping and wiring is the same.

The above described detailed description should not be taken asrestrictive of the invention as it is obvious that various changes indesign may be resorted to without departing from the invention asdeiined in the following claims.

l claim:

l. In a hydraulically actuated tool having a stationary work element anda movable work element cooperating with said stationary element, acylinder member adapted to be grasped in one hand of an. operator and anextension member adapted to be grasped in the other hand, a drivinglinkage operatively connected with said movable work element andreciprocably mounted in said extension member, a piston memberreciprocable in said cylinder member and connected with said drivinglinkage, a `conduit for introducing Huid under pressure into saidcylinder for so reciprocating said piston in one direction, spring meansfor urging said piston in the opposite direction, said extension memberand said cylinder member being swivelly connected to permit relativerotation of said members for angularly positioning said work elements asdesired, an electrical circuit including a switch on said tool and asolenoid actuated valve remote from said cylinder member for directingfluid to and from said cylinder.

2. In a hydraulically actuated tool having a stationary work element anda movable work element cooperating with said stationary element, acylinder member adapted to be grasped in one hand of an operator and anextension member adapted to be grasped in the other hand, an elongateddriving element operatively connected to said movable work element andreciprocable cylinder member and operatively connected with said drivingelement, means for introducing a fluid under pressure into said cylinderfor so moving said piston, and means swivelly connecting said cylinderand extension members and means swivelly connecting said piston memberand said driving element whereby said extension member may be rotated todifferent positions relative to said cylinder member as desired withoutrotating said piston.

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